The embodiments described herein relate generally to the field of ophthalmic therapies and more particularly to apparatus and methods fir delivering a drug to ocular tissue using multiple drug reservoirs.
Although needles have been used in transdermal and intraocular drug delivery, there remains a need for improved microneedle devices and methods, particularly for delivery of substances (e.g., drugs) into the posterior region of the eye. Many inflammatory and proliferative diseases in the posterior region (or other regions) of the eye require long-term pharmacological treatment. Examples of such diseases include macular degeneration, diabetic retinopathy, and uveitis. It is often difficult to deliver effective doses of a drug to the back of the eye using conventional delivery methods such as topical application, which has poor efficacy, and systemic administration, which often causes significant side effects. For example, while eye drops are useful in treating conditions affecting the exterior surface of the eye or tissues at the front of the eye, the eye drops are not significantly carried to the back of the eye, as may be required for the treatment of some of the retinal diseases listed above. Therefore, intraocular delivery of a drug is often desirable.
Some known intraocular delivery devices include a vial or reservoir that can store a substance prior to delivery into the eye. For example, in some known systems a drug can be disposed within an inner volume of a syringe (e.g., a reservoir) and the syringe can be coupled to a microneedle that is suitable for insertion into ocular tissue. In such configurations, however, the user's ability to control the volume of the drug dispensed can be limited.
Moreover, in such known systems, the drug disposed within the syringe can begin to separate during storage which can lead to reduced efficacy of the drug. Although, some known injection devices include multiple chambers and/or multiple reservoirs that allow for mixing or agitating of the drug prior to injection, such known injection devices are generally not configured to deliver drugs into the eye. For example, in such devices, the mechanism for transferring the drug from a first chamber to a second chamber can be complex, which can lead to a loss of accuracy in controlling the dosage delivered, an increase in cost of the device and the like. In some instances, one or more of the chambers included in such devices are disposed within a casing or the like that can limit visualization of the drug within the syringe, which can lead to the drug not be properly mixed or agitated prior to injection and can also limit proper metering of the dosage to be delivered.
Thus, a need exists for improved apparatus and methods for storing and mixing a drug in two or more reservoirs prior to delivery into ocular tissue.